In the past two decades the plumbing field has been revolutionized by the introduction of plastic pipe, drains, and fittings. The plastic materials are advantageous in their light weight, the ease with which they are worked, and the very simple processes which are required to join the various pipes and fittings together. Due to these qualities, many plumbing jobs have been greatly simplified. However, the use of plastic plumbing materials does have drawbacks. The most serious drawback of plastic materials is that the very method which facilitates simple joining of various plumbing parts also results in a permanent union between those parts. Unlike prior art metal plumbing fixtures, which can be unthreaded or desoldered, plastic fittings, when joined are permanently joined. Thus, although the plastic fittings are far easier to use, any error in their use is far more difficult to rectify.
For example, when a floor drain is being installed and assembled to a waste discharge pipe, it is common practice to install the floor drain mechanically into the drain hole, and to insert the waste discharge pipe in the drain fitting until it abuts an inner stop flange therein. Once the pipe and the drain fitting are joined by the adhesive or solvent, it is virtually impossible to separate them without destroying one or both of the parts. If these parts are joined and subsequently found to be less than perfectly sealed, the leak must be repaired by complete replacement of the drain fitting at the end of the pipe. This requires that the pipe be cut adjacent to the drain fitting, and the drain fitting must be entirely removed and discarded.